Mono- and di(functionally-substituted phenylene) semi-rigid crowns and precursors thereof

ABSTRACT

Bis(carboalkoxy-substituted m-phenylene)-32-crown-10 compounds, useful as polymerizable monomers, can be formed in one step by reacting a functionalized dihydroxy aromatic compound with a dihalopolyether. In the same reaction, carboalkoxy-substituted m-phenylene-16-crown-5 is formed. Other mono- and di-functionalized bis(phenylene) crown ethers can be made by one step as well as multistep synthesis from similar starting materials.

This is a division of application Ser. No. 07/574,633 filed Aug. 29,1990 now U.S. Pat. No. 5,142,068 which is in turn a continuation in partof Ser. No. 07/418,362 filed Oct. 6, 1989 and now U.S. Pat. No.5,028,731.

BACKGROUND OF THE INVENTION

It has recently been suggested that a family of polymeric analogs tomacromolecules, termed "polyrotoxanes", be synthesized using crownethers (or macrocyclic polyethers) as the cyclic component thereof. SeeH. W. Gibson et al., Polymer Preprints, 1988, 29(1) 248-249 and P. R.Lecavalier et al., Polymer Preprints, 1989, 30(1) 189-190, Ibid., 1990,31(2), 659-660.

It is known to form hetero crown ethers (also termed "corands")comprising oxygen atoms separated by (CH₂)_(n) groups and groups of theortho-phenylene type. See C. J. Pedersen, J. Am. Chem. Soc. 89 (1967)2495 and 7017. It is well known that such crown ethers can be used ascomplexation agents.

Chapoteau et al., in J. Org. Chem. 1989, 54, 861-867 mention that crownethers (corands) based on the 1,3-xylyl subunit have been synthesizedwith a variety of intraannular or inward facing groups includingmethoxyl, phenolic, carboxyl, methoxycarbonyl, hydroxyl, nitrile andsulfones.

Moore et al. in J. Amer. Chem. Soc. 99:19, 6398-6410 (1977) show certainmonobenzo-crown ethers containing outwardly facing substituents such as--CH₂ C₂ H₅ and --CN.

Allwood et al., in a series of reports in J. Chem. Soc., Chem. Commun.,1987, 1054-1064 illustrate a dinaphtho-crown ether (DN30C10 on pp.1054-1058), a non-substituted bismetaphenylene-32-crown-10 derivative(BMP32C10) on pp. 1058-1061, and a bisparaphenylene-34-crown-10derivative (BPP34C10) on pp. 1061-1064. The BMP32C10 derivative wassynthesized by partial benzylation of resorcinol to yield3-benzyloxyphenol which was reacted with tetraethylene glycolbis(toluene-p-sulfonate) (TEGBT) to yield1,11-bis(3'-benzyloxyphenoxy)-36,9-trioxaundecane. Deprotection of thatproduct followed by reaction of the derived diphenol with TEGBT affordedthe BMP32C10 derivative. Allwood et al. discuss the ability of BMP32C10and BPP34C10 to complex such materials as paraquat and diquat.

DESCRIPTION OF THE INVENTION

The present invention, in one embodiment, relates to a novel class of"functionalized" mono- and bis-phenylene-crown ether compounds, e.g.,those which may be broadly considered to be bis(extraannularfunctionalized substituted phenylene) crown ethers, for example,bis(carboalkoxy-substituted phenylene) 32-crown-10 compounds. The term"functionalized" as used herein is intended to cover substituents on thebis-or diphenylene moieties that are outwardly facing or "extraannular"so as to be capable of reaction with other monomeric compounds to formpolymers, such as polyesters, polyamides, polyimides and the like.Examples of such substituents include --COOH, --COCl, --OH, --R--OH(where R is alkylene or arylene), --NH₂, --R--NH₂ (where R is alkyleneor arylene) --SH, vinyl, or substituted vinyl. The instant inventionalso relates to precursors for making the "functionalized" mono- ordiphenylene-crown ether compounds described above as well as processesfor making the functionalized crowns and precursors.

The precursor compounds of the present invention when difunctionalizedcompounds are ultimately desired have the following formula: ##STR1##where Pr denotes the precursor group, e.g., lower alkyl, such as methyl,Ar denotes a phenylene ring, R is alkylene, e.g., ethylene, and n is aninteger from 1 to 8. When n is one and R is ethylene, a 32-crown-10structure is realized. The monoprecursors have the same formula depictedabove with one precursor group (Pr) not present.

The precursor compound, e.g., Pr=R (e.g., methyl), --OR (e.g., --OCH₃),X, --SR, --NO₂, or --NR₂, can be synthesized by the following four-stepprocedure, if desired. In this procedure, Pr is methyl. The first stepinvolves the reaction of a precursor-substituted dihydroxy aromaticcompound, e.g., 3,5-dihydroxytoluene (also termed "orcinol monohydrate")with a halopolyether (e.g., chloropolyether) containing a hydroxyprotecting group, such as tetrahydropyranyl, on one end thereof to forman initial reaction product: ##STR2## where Pr denotes the precursorgroup, R₁ is the hydroxy protecting group, Ar denotes the phenylenering, and --OR(OR)_(n) OP is derived from the halopolyether with R beingalkylene (e.g., ethylene), and n being from 1 to 8. The reactionconditions can be as follows: sodium hydroxide as base, 1-butanol assolvent at reflux for thirty hours.

The reaction product is then acid-catalyzed deprotected under inert gas(e.g., nitrogen) to form the corresponding diol upon removal of theprotective group P.

The resulting diol is then reacted with tosyl halide (e.g., tosylchloride) using an amine acid acceptor in order to form thecorresponding tosylate.

The cyclization reaction to form the precursor to the final crown etherproduct is accomplished by reacting the foregoing tosylate with thepreviously described diol, e.g., (or an analogous diol with n being of adifferent value) in the presence of an appropriate solvent (e.g.,tetrahydrofuran). The final product can be envisioned as having theformula: ##STR3## where Pr, Ar, R, and n are as described above. In thecase of a 32-crown-10 product, n will be equal to 1 and R is ethylene.

The aforementioned precursor crown, containing a lower alkyl precursormoiety (Pr), such as methyl, can be converted to certain of thefunctionalized crown ether compounds to be described below byappropriately converting the alkyl group into a functional group capableof polymerization. For example, a carboxylic acid functional group isderivable by oxidizing the alkyl precursor moiety Pr using conventionaloxidants, such as potassium permanganate. Once the carboxylic acidfunctional group is obtained, it can be converted, if desired, toalkylenehydroxy (e.g., --CH₂ OH) by appropriate reduction, e.g., usinghydride reducing agents or it can be converted to --C(O)X, X being halo,such as chlorine, by using a suitable halogenating agent, e.g., sulfonylchloride or phosphorus trichloride.

A one-step process for forming the aforementioned type of precursorcrown ether product has also been developed in which the aforementionedprecursor-substituted dihydroxy aromatic compound (e.g., orcinolmonohydrate) previously described for use in the four-step method isreacted with a poly(alkylene glycol) ditosylate of the general formulaTs(OR)_(n) OTs, where Ts is tosylate, R is alkylene, e.g., ethylene, andn is an integer from 1 to 12. This reaction is preferably carried out inorganic solvent (e.g., dioxane plus 1-butanol) under reflux using base(e.g., sodium hydroxide). A novel 16-membered crown ether by-product,also useful as a complexation agent, produced by the one-step process is5-methyl-(1,3-phenylene) 16-crown-5. Such monofunctional mono-phenylenecrown ethers can also be converted by methods similar to those notedabove to polymerizable monomers, e.g., by incorporation of vinyl groupsor conversion to derivative diols or diacids. The vinyl monomer typeswill produce polymers with pendant crown ethers which are also suitablefor complexation and membrane applications.

The process used herein is one in which a functionalized dihydroxyaromatic compound is reacted with a halopolyether (e.g., achloropolyether) containing a hydroxy protecting group at one endthereof, such as tetrahydropyranyl to form an initial reaction product:##STR4## where R₂ denotes the functional group, Ar denotes the phenylenering, and --OR(OR)_(n) OP is derived from the halopolyether with R beingalkylene (e.g., ethylene), n being from 1 to 8, and R₁ being theprotective group. The reaction conditions can be as follows: sodiumhydride (NaH) as base, dimethylformamide as solvent at 25° C. to 100° C.for up to five days under an inert gas (e.g., nitrogen).

The reaction product is then acid-catalysis deprotected under inert gas(e.g., nitrogen) to form the corresponding diol upon removal of theprotective group R₁.

The resulting diol is then reacted with tosyl halide (e.g., tosylchloride) using an amine acid acceptor in order to form thecorresponding tosylate.

The cyclization reaction to form the final crown ether product isaccomplished by reacting the foregoing tosylate with the previouslydescribed diol, e.g., (or an analogous diol with n being of a differentvalue) in the presence of an alkali metal hydride in an appropriatesolvent (e.g., tetrahydrofuran). The final product can be envisioned ashaving the formula: ##STR5## where R₂, Ar, R, and n are as describedabove. In the case of a 32-crown-10 product, n will be equal to 1 and Ris ethylene.

While the foregoing discussion illustrated the preparation of crownethers where oxygen atoms constitute the hetero atoms it is to beunderstood that one or more of such oxygen atoms can be replaced, forexample, with nitrogen to form aza crown compounds.

The instant invention is illustrated by the Examples which follow.

EXPERIMENTAL

General comments. All melting points were taken in capillary tubes witha Haake Buchler melting point apparatus and have been corrected. ¹ H and¹³ C NMR spectra were obtained at ambient temperature indeuteriochloroform solutions with Me₄ Si as internal standard (δ=0 ppm)and recorded on a Bruker WP high resolution spectrometer operating at270 MHz. Infrared spectra were recorded on a Nicolet MX-1 FTIRspectrometer. Mass spectra were measured with a VGA 7070E Analyticalmass spectrometer. Elemental analyses were performed by AtlanticMicrolab of Norcross, Ga.

Materials. Unless specified otherwise, reagent grade reactants andsolventswere used as received from chemical suppliers. Tetrahydrofuranwas refluxedover Na/benzophenone and was used immediately. Thetetrahydropyranyl ether of 2-(2'-chloroethoxy)ethanol was prepared byfollowing a literature procedure. (E. P. Kyba et al., J. Am. Chem. Soc.1977, 99, 2564).

EXAMPLE 1

This illustrates a one-step procedure for forming a bis(carbomethoxy)crownand a novel 16-crown-5 by-product.

Tetraethylene glycol dichloride (13.15 gm, 0.05 mole) in 250 mldimethylformamide (DMF) was added to 225 ml of DMF containing 9.58 gm(0.05 mole) of methyl 3,5-dihydroxybenzoate and 2.76 gm (0.115 mole) ofsodium hydride. The solution was stirred vigorously at 75° C. fortwenty-four hours under a blanket of nitrogen, cooled, filtered andevaporated to give a brown viscous oil residue, which waschromatographed on silica gel (7 gm per 1 gm crude products) withdiethyl ether as eluent to produce the corand,bis(5-carbomethoxy-1,3-phenylene)-32-crown-10 as a crystalline solid, 2gm, 11% yield, mp 105.5°-106.5° C., IR (KBr pellet) 1717 (C═O), 1600(C═C), 1067-1137 (C--O--C) cm⁻¹, ¹ H NMR (CDCl₃ /TMS) δ 3.6-4.3 (38H, m,OCH₂ and OCH₃), 6.7 (2H, s, Ph-H_(-b)), 7.15 (4H, s, Ph-H_(-a)); m/z(EI⁺): 652 (M⁺), 621 (M⁺ -OCH₃), 590(M⁺ -20CH₃). Anal. Calcd. for C₃₂H₄₄ O₁₄ (MW 652): C, 58.88; H, 6.80. Found: C, 58.67; H, 6.86.

5-carbomethoxy-1,3-phenylene-16-crown-5 was isolated from the abovereaction products, 1.59 gm, 9% yield as a needle-like crystalline solid,mp 71°-72° C., ¹ H NMR (CDCl₃ /TMS) δ 3.5-4.4 (19H, m, OCH₂ and OCH₃),7.2 (2H, s, Ph-H_(-b)), 7.35 (1H, s, Ph-H_(-a)); m/z (EI⁺): 326 (M⁺),295 (M⁺ -OCH₃), 267 (M⁺ -COOCH₃), 239 (M⁺ -COOCH₃ and CH₂ CH₂). Anal.Calcd. for C₁₆ H₂₂ O₇ (MW 326): C, 58.89; H, 6.80. Found: C, 58.96; H,6.83.

EXAMPLE 2

This illustrates the one-step process for formingbis(5-methyl-1,3-phenylene)-32-crown-10 and1,3-(5-methylphenylene)-16-crown-5.

Tetraethylene glycol ditosylate (50.23 gm, 0.100 mole) in 500 mldioxane/1-butanol (3:2 v/v) was added to 450 ml of 1-butanol containingorcinol monohydrate (16.40 gm, 0.115 mole) and sodium hydroxide (9.10gm, 0.230 mole) in 8 ml of water. The solution was refluxed fortwenty-four hours, under a blanket of nitrogen, cooled, filtered andevaporated to give a brown viscous oil, which was chromatographed onacidic alumina withethyl ether to producebis(5-methyl-1,3-phenylene)-32-crown-10, 2.5 gm, 9% yield (mp and othercharacteristic data reported below in Example 6) and1,3-(5-methylphenylene)-16-crown-5 as a needle-like crystalline solid.1.6gm, 7% yield, mp 69°-71° C., ¹ H NMR (CDCl₃ /TMS) δ 2.25 (3H, s,Ph-CH₃), 3.60 (4H, t, δ-OCH₂), 3.70 (4H, t, δ-OCH₂), 3.82 (4H, t,β-OCH₂), 4.27 (4H, t, α-OCH₂), 6.37 (2H, s, Ph-H_(b)) and 6.92 (1H, s,Ph-H_(a)) for H_(a) and H_(b) ; m/z, (EI⁺): 282 (M⁺) , 195 (M⁺ -OCH₂ CH₂OCH₂ CH₂), 168 (M⁺ -CH₂ CH₂ OCH₂ CH₂ OCH₂ CH₂), 151 (M⁺ -OCH₂ CH₂ OCH₂CH₂ OCH₂ CH₂), 124 (M⁺ -CH₂ CH₂ OCH₂ CH₂ OCH₂ CH₂ OCH₂ CH₂); Anal. CalcdforC₁₅ H₂₂ O₅ (MW 282): C, 63.81; H, 7.85. Found: C, 63.67; H, 7.86.

EXAMPLE 3

This Example illustrates the first step in the four-step procedure forpreparing the precursor crown ether,bis(5-methyl-1,3-phenylene)-32-crown-10.

Following a literature procedure (M. Newcomb et al., J. Am. Chem. Soc.1977, 99, 6405), a solution of 2-(2'-chloroethoxyethyl)tetrahydropyranyl ether (55.50 gm, 0.266 mole) in 150 ml 1-butanol,containing orcinol monohydrate (11.00 gm, 0.077 mole) and sodiumhydroxide (7.50 gm. 0.185 mole). The resulting mixture was refluxed forfifteen hours and an additional amount of sodium hydroxide (2.60 gm,0.065 mole) was added. After an additional fifteen hours at reflux,sodium chloride (14.0 gm) wasfiltered from the cooled reaction mixture,which was evaporated. Unreacted tetrahydropyranyl ether was removed bydistillation from the residue, to give the compound3,5-bis(5-tetrahydropyranyloxy-3-oxa-1-pentyloxy)toluene: 33.0 gm, 95%,oil; IR (neat) 1600 (C═C), 1129 (C--O--C) cm⁻¹ ; ¹ H NMR (CDCl₃ /TMS δ1.3-1.9 (12H, m, CH₂), 2.25 (3H, s, Ph-CH₃), 3.5-4.1 (20H, m, OCH₂), 4.6(3H, s, O--CH--O ) and 6.35(3H, s, Ph-H).

EXAMPLE 4

This illustrates the next step in the synthesis using the product fromExample 3.

The above bistetrahydropyranyl ether from Example 5 (33.00 gm. 0.070mole) was dissolved in 500 ml CH₃ OH:CH₂ Cl₂ (1:1 v/v) and 5 mlconcentrated hydrochloric acid was added. The solution was stirred for 4hours at room temperature, then neutralized with NaHCO₃. The organiclayer was separated, dried over magnesium sulfate, filtered and thesolvent was removed in vacuo. The residue was distilled to give the diol3,5-bis(5-hydroxy-3-oxa-1-pentyloxy)toluene: bp 195°-197° C./0.05 mm,19.2 gm, 92%; IR (neat) 3405 (O--H), 1600 (C═C), 1129 (C--O--C) cm⁻¹ ; ¹H NMR (CDCl₃ /TMS) δ 2.25 (3H, s, Ph-H), 2.8 (2H, br, s, OH), 3.5-4.2(16H, m, OCH₂) and 6.35 (3H, s, Ph-H).

EXAMPLE 5

The third step in the four-step synthesis for makingbis(5-methyl-1,3-phenylene)-32-crown-10 is described herein.

Literature procedure (M. Ouchi, J. Org. Chem. 1984, 49, 1408) wasgenerallyfollowed. It was modified by using a reaction time oftwenty-four hours instead of two hours at 0° C. This allowed for a 97%yield of the ditosylate (literature: 81%) without the necessity of usingcolumn chromatography for purification. The excess of p-toluenesulfonylchloride was removed from the reaction product simply by washing withhexanes.

Separate solutions of the diol from Example 6 (10.00 gm, 0.033 mole) in37 mmole (6 ml) of dry pyridine and p-toluenesulfonyl chloride (19.25gm, 0.100 mole) in 77 ml of pyridine were cooled to -20° C. Thesolutions were then combined and maintained at -20° C. for seventy-fourhours while stirring. The reaction mixture was then poured into 240 mlice water, and this mixture was extracted with three 120 ml volumes ofdichloromethane. The combined organic phase was washed with three 170 mlportions of ice cold 6N aqueous HCl and then with 150 ml of saturatedaqueous ammonium chloride. After drying of the organic phase overanhydrous magnesium sulfate and filtration, removal of solvent underreduced pressure yielded the ditosylate3,5-bis(5-toluenesulfonyloxy-3-oxa-1-pentyloxy)toluene: viscous oil, 19gm, 97%; IR (neat) 1355, 1190 and 1175 (S═O), 1600 (C═C), 1129 (C--O--C)cm.sup. -1 ; ¹ H NMR (CDCl₃ /TMS) δ 2.25 (3H, s,Ph-H), 2.4 (3H, s, O-SO₂-Ph-CH₃), 3.7-4.3 (16H,m, OCH₂), 6.2-6.4 (3H, m, Ph-H), 7.55 (8H, AB, q,O-SO₂ -Ph-H).

EXAMPLE 6

This illustrates the final step in the four-step synthesis for makingbis(5-methyl-1,3-phenylene)-32-crown-10.

To a solution of 3,5-bis(5-hydroxy-3-oxa-1-pentyloxy)toluene (1.50 gm, 5mole) in 75 ml THF (dried over sodium/benzophenone) was added potassiumt-butoxide (1.6 gm, 15 mmole), and the solution was stirred undernitrogenfor one hour. A solution of3,5-bis(5-toluenesulfonyloxy-3-oxa-1-pentyloxy)toluene (3.0 gm, 5 mmole)in 37 ml THF was added, the mixture was stirred at room temperature forfive days and then refluxed for thirty-six hours. The solvent wasevaporated in vacuo, and the residue was partitioned between 100 ml ofCH₂ Cl₂ and 100 ml of water. The organic layer was dried over sodiumsulfate and evaporated in vacuo, to give a brown viscous oil, 2.5 gm,which was chromatographed on 75 gm neutral alumina with ethylacetate-petroleum ether (2:1 v/v) as eluent to produce 0.8 gm, 25% ofdesired macrocycle as a white solid, mp, 94°-96° C.; IR (KBr) 1129(C--O--C) cm⁻¹ ; ¹ H NMR (CDCl₃ /TMS) δ 2.25 (6H, s, Ph-H); 3.7 (16H, s,γ/δ-OCH₂), 3.82 (8H, t, β-OCH₂), 4.05 (8H, t, α-OCH₂), 6.32 (6H, s,Ph-H); m/z (Cl⁺): 565 (M⁺ +1), 521 (M⁺ -OCH₂ CH₂); Anal.Calcd for C₃₀H₄₄ O₁₀ (MW 564): C, 63.81; H, 7.85. Found: C,63.74; H, 7.86.

EXAMPLE 7

This illustrates the first two steps in the synthesis of5-methyl-bis(1,3-phenylene)-32-crown-10.

A solution of 34 gm (0.163 mole)2-(2'-chloroethoxyethyltetrahydropyranyl ether in 75 ml of 1-butanol wasadded dropwise to a mixture of (5.5 gm, 0.05 mole) of resorcinol and(4.1 gm, 0.1 mole) of NaOH in 150 ml of boiling 1-butanol. The resultingmixture was stirred under reflux for fifteen hours, and an additional1.5 gm (0.03 mole) of NaOH was added after an additional fifteen hoursat reflux. The cooled reaction mixture was filtered from NaCl (11.0 gm)and concentrated in vacuo to remove solvent and low boiling components.A viscous oil (16.5 gm) was obtained. The oily residue was dissolved in300 ml CH₃ OH:CH₂ Cl₂ (1:1 v/v) and 4 ml concentrated hydrochloric acidwas added, the solution was stirred for three hours, neutralized withNaHCO₃, and extracted with three portions of 150 ml chloroform. Thecombined organic phase was dried over magnesium sulfate, the solvent wasremoved in vacuo, and the residue was distilled to give1,3-bis(5-hydroxy-3-oxa-1-pentyloxy)benzene:bp 190°-195° C./0.1 mm (mp36°-38° C.), 12 gm, 91%; IR (neat) 3405 (O--H) 1600 (C═C) 1129 (C--O--C)cm⁻¹ ; ¹ H NMR (CDCl₃ /TMS) δ 3.35 (2H, s, OH), 3.55-4.3 (16H, m,OCH₂),6.7-7.22 (4H, m, Ph-H).

EXAMPLE 8

This illustrates the final step (cyclization) in the synthesis of5-methyl-bis(1,3-phenylene)-32-crown-10.

To a solution of 2.86 gm (10 mmole) of the diol from Example 7 in 150 mltetrahydrofuran (THF) (freshly distilled over sodium/benzophenone) wasadded 2.8 gm (25 mmole) of t-BuOK, and the solution was stirred undernitrogen for one hour. A solution of 6.0 gm (10 mmole) of the ditosylatefrom Example 5 in 74 ml THF was added, the mixture was stirred at roomtemperature for 5 days and then refluxed for thirty-six hours. Thesolventwas evaporated in vacuo, and the residue was partitioned between200 ml of CH₂ Cl₂ and 200 ml water. The organic layer was dried overmagnesium sulfate and evaporated in vacuo, to give a brown viscous oil(7.0 gm), which was chromatographed on 200 gm neutral alumina with ethylacetate petroleum ether (2:1 v/v) as eluent to produce the titlemacrocycle, 1.1 gm, 20%, as a white crystalline solid, mp 66°-68° C. IR(KBr), 1600 (C═C), 1129 (C--O--C) cm⁻¹ ; ¹ H NMR (CDCl₃ /TMS) δ 2.25(3H, s, Ph-CH₃), 3.65 (16H, s, γ/δ-OCH₂), 3.85 (8H, t, β-OCH₂), 4.1 (8H,t, α-OCH₂), 6.34 (3H, s, Ph-H_(c)), 6.5 (3H, d, Ph-H_(b),) 7.12 (1H, t,Ph-H_(a)); m/z, (EI⁺): 550 (M⁺) 283 (M⁺ -CH₂ CH₂ OCH₂ CH₂ OC₆ H₄ OCH₂CH₂ OCH₂ CH₂ OCH₂). Anal. Calcd for C₂₉ H₄₁ O₁₀ (MW 550): C, 63.37;H,7.52. Found: C, 63.17; H, 7.71.

We claim:
 1. Bis(extraannular functionally-substitutedphenylene)-32-crown-10 compounds which are 5-carboalkoxy substituted. 2.Compounds as claimed in claim 1 wherein the carboalkoxy moiety iscarbomethoxy.
 3. Extraannular functionally-substitutedphenylene-16-crown-5 compounds which are 5-carboalkoxy-1,3-phenylene. 4.Compounds as claimed in claim 3 wherein the carboalkoxy moiety iscarbomethoxy.
 5. Bis(extraannular alkyl-substitutedphenylene)-32-crown-10 compounds which are 5-methyl-1,3-phenylene. 6.1,3-(5-methylphenylene)-16-crown-5.
 7. Extraannular mono- oralkyl-substituted bis(phenylene)-32-crown-10 compounds which are5-methyl-bis(1,3-phenylene.
 8. Extraannular mono-carboalkoxybis(phenylene)-32-crown-10 compounds which are 5-carboalkoxybis-(1,3-phenylene).
 9. Compounds as claimed in claim 8 where thecarboalkoxy is carbomethoxy.